Polymerization of butadiene-1, 3 hydrocarbons



ranma .my 31. 1945 UNITED STATES rArsN'r ori-'lcs ron'non or sonoma-'1.8rrrlmooannous` 10 Claims. (Cl,

I This invention relates to the polymerization ot butadiene-1,3hydrocarbons. and particularly 'to a method whereby butadiene-1,3hydrocarbons may be polymerlzed in aqueous emulsion to form productsclosely resembling The emulsion polymerization o! butadiene-1,3hydrocarbons either alone or in admixture with other monomerscopolymerimble therewith to form compositions fot matter more or lessresembling rubber is well known. It has been commonly observed,hoyvever, that the products oi.' such polymerization reactions oftenresemble vulcanized rubber rather than natural crude rubber in respectto solubility, plasticity, and processing characteristics. \Thus thatthe polymers were insoluble in. and. in some cases, not even swelled bybenzene or acetone. and that they were tough, non-plastic materialswhich either would not homogenize on a mill or which were very difficulttoV mill and to subject to other ordinary processing operations.

I have now discovered a class of materials which modmestne emulsionpolymerization of butadiene-1,3 hydrocarbons in such a manner thatpolymers more nearly resembling natural crude rubber may be producedthan when the polymerization is effected in. the absence o! thematerials of this invention. This class or materials, which I havetermed modifiera consists of compounds containing the sroup wherein Xrepresents omen or sulfur. Compounds containins this group may bereadily prepaxedby the reaction of an alkali metal zanthate with aphosphorus oxyhalide orl a phosphorus thiohalide such as phosphorusoxychloride, phosl natural crude rubber.

it has often been foundv hisiisopropoxythionmtrithiophosphate, tris(ter.butylexythlonmtrithlophospha, and the tris- (alkoxythlono)tetrathlophosphates such as tria- (ethowthiono) tetrathiophosphate,cnn-o-c-s Eras l are the preferred classes oi compounds because ot theircomparatively low cost and the ease with which they may be prepared, butany other com-l pound contamina the group -x-ov-shrx may be employed i!desired.

As a speciilc example of this invention, a mixture o! 55 parts by weightoi butadiene and 45 parts ot acrylonitrile was agitated' at 30 C. in thepresence oi about 250 parts oi an aqueous solution .of myristic ac'dwhich had been about 85% neutralized with sodium hydroxide, 0.35 part ot'hydrogen peroiilde as an initiator, 0.1 part of terri pyrophosphate asa catalyst. and

1.0 part of trisiisopropoxythionoltrithiophosphate. Coagulation o! thelatex-like obtained as the product yielded da plastic, ooherent polymerwhich was 95.8% soluble in acetone. Repetition ot the above experimentin the absence of a modiner produced a polymer which was non-plastic,non-coherent. and which was only 1% soluble in When the modiiled polymerwas compared further with the unmodiy.ned polymer, it was round that themodiiied polyon the mill, the the modled polyand' the tensile hier wasmuch easier to work dispersion ot tue pigments in mer was considerablybetter.

strength and elongation o! avulcanizate prephorus oxybromide, orthiophosphoryl' chloride (B=P`5Cls). The reaction o!- potassium ethylxanthate and phosphorus oxychlorlde is described by Richter, B. 49, 1028(1918). Analogous reactions may -be'ernployed to produce other modiiiersherein described The xanthate may be derivedtrom an alcohol or a thiolsuch as ethanol. allyl alcohol. cyclohexyl alcohol. tetrahydnofmiurylalcohol, benzyl alcohol, isopropyl mercaptan, etc., by -a reaction withcarbon disulde and analkall in known manners'. The `izrlslkoxy--thiononrithiophosphates such as tris(etbyl0xy pared trom the modied"polymer were much nicher. l Qtber modiiiers such astrisitetrahydroturiuryloxythionoitrithiopnosphate, trisiethoxythionn)tetrathiophosphate, and' trisilsopropoxy- `thiono) tetrathiopnosphatemay beemployed as I the modiner with equivalent results.- v

thiono)trlthiophosphaterepresentedbythestruc The propo inwnichthemodiiler is in- 'cluded inthe composition' depends somewhatuponthcpropertiesdesiredintheproducathe hisherpmportionsot modiiier ingeneral PN- ducmg soitenmore soluble polymers. AVer-yema!! amounts'otmodier suon as 0.1%, or even lessbasedonthemonomersintheemulsion'mayproioundly ailect the nature orthe'polymer produced, and amountsup to 5% crmoxeml!advantaleoullybeemployed. Itinayalso be advantsgeoitoemployamixtureotthemodiiierl 2 i assecoo and 2,3-dimethy1butadia1e, either alone or inadmixture with each other and/or other monomers copolymerizabletherewith such as styrene, isobutylene, acrylonitrile, methylmethacrylate. methyl acrylate. methyl vinyl ether, methyl vinyl ketone,and other unsaturated hydrocarbons, es-

ters, ethers, and ketones. For the production ci robbery products, theseother monomers. should be employed in an amount smaller than thebutadiene. The polymerization of the above materials in aqueous emulsionmay be eilected by various initiators oi polymerimtion such asper-compounds including per-acids, `peroxldes, and per-salts such.

as persuliates, perborates, percarbonates, and the like aswell as othertypes'ofinitiators such as v obenxene, bisuliites. -hydll'iuulillis.Bind `diilotassium diasometbane disuli'onate.

The polymerization reactions may be catalyzed 30inanydesiredmanner,theuseofheavymetal catalysts being particularlydesirable.A The heavy metal catalyst may be added to the emulsion inthei'orm cilesstha'n 0.1% basedon the weishtoi' Iclaim:1.'.lhemetbodwhichoomprisesvolymerisinga `butadiene-1,3 hydrocarbon inthe icrm oi an aqueous emulsion in the presence oi a smallamountoi'acompoinidcontainingthearo'upy x--s mwhereinxisamemberoithesroupeonsistingot 10 oxygen md Sulfur.

2. The method which comprises polymerizinz in the form oi an aqueousemulsion a mixture ct butadiene and a smaller amount oi' a monomercopolymerisable therewith in aqueous emulsion.inthepresenceotasmallamountofacompound containing the from:

(-x s Era-tx e l 2whereinlisaincnllaerotthegroupconsisting oi oxygen andsulfur. l.

3. The method which comprises polymerizins inthe form oi on aqueousemulsion a mixture of a. butadiene-1,3 hydrocarbon and a smaller amountof a monomer copolymerizable therewith in aqueous emulsion, in thepresence oi' a trisialkonthiono) trithiophosphate.

.4. The method which comprises polymerizins in the form ot anaqueousemulsion a mixture of a butadiene-1,3 hydrocarbon and a smalleramount of a monomer eopolymerisable therewith inaqueous emulsion, in thepresence of trisdsoprODoxythiono) trithiopholphote. l

5, The method which comprises polymerising in the monomers oi' a simpleionizable heavy metal 35 'the form .f m mem mum@ a mixture 0f 3 salt.such ascobalt chloride; nickelous sulfate, mercurio chloride, ete., asdmclosed in the copending application of WilliamD. Stewart, Serial No.379,712 led February 14, 1941, 0l' in the i'rm of a redox systemcomprising a heavy metal and A4'0 s m method which mm mem a a materialsuch as sodium pyrophosphate, levulinic acid, glycine, cystine,beta-mercaptoethanol. quebrachitol, usabile or cholesterol as 'disclosedin the copending application oi William D. Stewart, Slilal Nos. 379,713to 379,717 filed February 14,

1 Any ofthe emulsitying agents known tobeuseful in connection with theemulsion polymerization oi butadiene hydrocarbons may be employed. TheiJOlymerizations may be eiected under acid conditions' by employing -asemulsifying Vagents salts of organic bases containing long carbon chainssuch as the hydrochloride oi diethylaminoethyloleylamlde. thehydrochloride oi' the diethylamine of oleic acid, trimethylcetylammoniumsulfate, etc.; under alkaline conditions by employing soaps such-assodium oleate, sodium myristate, potassiumrpalmitate, etc.. and underacid; alkaline, or neutral conditions by employing synthetic materialssuch as hymolal suli'ates or alkaryl sulionates including sodium:attieryl sulfate, sodium isobutyl naphthalene sula ,eta vjA Although Ihave disclosed speciile embcdiments of my invention; I do not intend tolimit the invention solely thereto. for it will beobvioustothoseskilledintheartthatmanyvariationsandmodiilcationsarewithinthespiritand .-scopeottheinventionssdciinedintheappended butadiene-1.3hydrocarbon and a smaller amount ot a monomer. copolymer-trahietherewith in aqueous emulsion, in the presence of a trisialkcxythiono)tetrathiophosphate.

mixture oibutadiene and a smaller amount oi' acrylonitrile in the formoi an aqueous emulsion in the presence ot a compound containing thegroup 4s- A' (-xl'A .aux

Yvlhereinxisamemberoithesroupot 7. The method which comprises a 5mixture ofbutadiene'and'a smaller amolmtotacrylonitrileinthetormotanaqueousemulsion in the lpresence of atris(alkoxythiono) trithio- 55 8.'lhe method which commisespolymerisingamixtureotbutadimelndasmalleramountotacrylonitrileinanaqueousemulsioninthepsence of tris(isopropoxythiono)triththiophospbate. 9. The method4 which comprises polymerizing a wmixture of butadiene and a smaller amount of acrylonitrileinanaqueomemulsioninthe prese ence of a tris(alkowthiono)tetrathiophosphate.

10. The method which comprises polymerixinsamixtureoibutadieneandasmalleramolmtotstyreneinanaqueous-emulsioninthepresence oi amscalkoxytmonomitniopnospmte.

Glorias L. mowNmo, Ji.

